| Abstract
| - A Sn-free electroless plating process for producing patterned and adherent copper deposits on (100)-orientedsingle-crystal silicon substrates is described. Pristine and resist-patterned Si(100) substrates were etched, initially,by aqueous HF to produce the hydrogen-terminated silicon surfaces (H−Si(100) surfaces). The H−Si(100)surfaces were further functionalized by the UV-induced reactive coupling of 4-vinylpyridine (4VP). Thecomposition and topography of the modified Si(100) surfaces were characterized by X-ray photoelectronspectroscopy and atomic force microscopy, respectively. The coupled 4VP layer exhibited good stability inboiling chloroform, boiling water, sonicating dichloromethane, aqueous solution of HF and aqueous solutionof KOH. Not only did the 4VP layer provide chemisorption sites for the palladium complexes without theneed for prior sensitization in SnCl2 solution during the electroless plating process but it also served as theadhesion promotion layer and diffusion barrier for the electrolessly deposited copper. The 180°-peel adhesionstrength of the electroless deposited copper on the modified silicon surface was dependent on the extent of4VP surface coverage and could reach about 4 N/cm.
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